The oxidation of ethanol was studied in low-pressure, premixed flat flames using molecular beam mass spectrometry (MBMS) in combination with electron impact ionization (EI) and resonance-enhanced multiphoton ionization (REMPI). Flame temperature profiles were measured by laser-induced fluorescence (LIF) of seeded NO. Two ethanol/oxygen/argon flames with stoichiometries of phi = 1.00 and phi = 2.57 were investigated at 50 mbar by EI-MBMS. Profiles of a variety of stable and radical species were measured as a function of height above the burner. The benzene profile in the fuel-rich ethanol flame was obtained by REMPI-MBMS. The same technique was used to determine the dependence of the benzene concentration on the ethanol/propene ratio in low-pressure flames with blended fuels (propene/ethanol/oxygen/argon). The C/O ratio of all blends was kept constant at C/O = 0.773 or C/O = 0.600. Ethanol addition ranged from 0 to 15% for flames with C/O = 0.773, and from 0 to 100% for flames with C/O = 0.600. In both data sets, a decrease of the benzene concentration with increasing ethanol percentage was observed. Qualitative information on some other aromatic species with higher mass was also obtained. (c) 2007 Published by Elsevier Inc. on behalf of The Combustion Institute.